1.^,6 



NA 1 URE 



[April i, 1909 



■one basic furnace and then transferring the metal, but 

 not the slag, to a second furnace, completing the 

 purification and finishing the steel in the second 

 furnace. The slag of the primary furnace is valuable, 

 and the removal of the phosphorus before the carbon 

 is a great advantage. This process has met with 

 considerable success. In 1898 Talbot introduced his 

 continuous process, which is so well known that it 

 need hardly be described. 



In 1900 Monell patented a process which has come 

 into considerable public prominence owing to a 

 recently decided law case with regard to its alleged 

 infringement. In certain circumstances the amount of 

 scrap required for the ordinary working of the basic 

 open-hearth process is not easily obtained, and 

 although by the ordinary process an all-pig charge 

 may be successfully worked, the time occupied in 

 getting rid of the large quantity of impurities in- 

 creases the length of time necessary for purification, 

 and hence decreases the output of a furnace of a given 

 size. Monell charges on to the bottom of the open- 

 hearth the usual quantity of limestone which was 

 employed in a furnace of like capacity with charges 

 of half pig and half scrap. But along with this lime- 

 stone he charges an amount of oxide of iron, gener- 

 ally in the form of iron ore, equal to about 20 per cent. 



■ of the weight of the pig-iron it is proposed to treat. 

 These materials are heated to a red heat, and whilst 

 still unfused the charge of pig-iron in the molten 

 condition, either direct from the blast furnace or 

 from a metal mixer, is poured into the furnace as 

 rapidly as possible. This causes an active reaction, 

 and the materials being at a comparatively low 

 temperature the ore oxidises the phosphorus, silicon, 

 and manganese in the pig-iron with extreme rapidity, 

 and at the same time oxidises a portion of the carbon. 

 If the phosphorus in the original pig be not more 

 than o'8o per cent., in about one hour it will be 

 reduced to less than o'l per cent., the carbon remain- 

 ing being about 2 per cent. Eighty per cent, of the 

 slag is now removed, leaving the metal only very thinly 

 covered, and then oxide of iron is added to the bath 

 and the carbon gradually reduced to the percentage 

 required ; so that by this means, in the basic furnace, 

 a steel sufiicienth' low in sulphur and phosphorus is 

 produced, and of any carbon desired, without the 

 necessity of going down to a very low percentage of 

 carbon, as in the ordinary process, and either being 

 ■content to make only mild steel or to make special 

 arrangements for carburising after removal of the 

 slag (the Darby process). The yield by the Monell pro- 

 cess is more than 100 per cent, of the metallic charge, 

 owing to reduction of iron from the ore, the mean 

 of about eighty consecutive trial heats being 108 per 

 cent., but this is a feature not peculiar to this 

 modification only. Unfortunately for the usefulness 

 of the Monell process in this country, when the pig- 

 iron contains from r5 per cent, to 2'o per cent, 

 phosphorus, as only about 80 to 90 per cent, of the 

 total phosphorus is removed, too much remains in 

 the metal at the end of the reaction to make the 

 process valuable, and after the removal of the first 

 slag, additions of lime and ore must be made as in 

 ordinary working. 



Improvements made in the basic process even since 

 1900 have rendered the application of the Monell 

 process unnecessary in this country. Metal mixers, 

 large vessels in which molten iron from the blast 

 furnace is stored, were originally used mainly to 

 obtain a more regular composition of iron for either 

 the converter or the open-hearth process. Gradually 

 these have developed in size from a capacity of about 

 70 or 80 tons up to the present day, when mixers 

 of 200 to 600 tons capacity are used, and the metal- 



NO. 2057, VOL. 80] 



mixer is now often gas-fired, so that the heat of 

 the metal can be maintained for longer periods, and 

 even cold pig-iron can be added. The metal mixer 

 is now much used as a furnace for the preliminary 

 purification of the molten cast-iron froni the blast 

 furnace. The modern metal mi.xers are lined with 

 dolomite or magnesia, are gas heated, oxides of iron 

 are added to the contents, and the blast-furnace metal 

 made and cast into pigs during week-ends, and 

 generally called week-end metal, can be melted 

 in them. At the comparatively low temperature 

 maintained in the mixers (about 1500° C.) silicon 

 and phosphorus are partially eliminated, whilst 

 the carbon is but little affected. The sulphur 

 is decreased because of the length of time the metal 

 is lying in a molten condition in the mixer, during 

 which the manganese sulphide gradually floats to 

 the top and is removed with the slag. The resulting 

 metal is in good condition, arid of suitable composition 

 to be transferred to the ordinary basic open-hearth 

 furnace and finished with a comparatively clean slag 

 — that is, a slag not rich in phosphate. 



From the results given by Mr. A. Windsor Richards 

 in a paper to the Iron and Steel Institute recently, it 

 would seem as if the basic Bessemer process had 

 received, through the modification in its working 

 designed by Dr. Massenez, an efficient tonic in its 

 desperate struggle with the open-hearth process. By 

 this modification the ordinary high-silicon low- 

 sulphur Cleveland pig (c), made from native ores, is 

 poured in a molten condition into a basic lined 

 converter, into which has been previously placed iron 

 ore, with a small quantity of lime. The blow is 

 continued until the carbon flame appears and all the 

 silicon is oxidised, when the converter is turned down 

 and the slag is carefully removed, this slag containing 

 35 to 45 per cent, silica and practically no phosphate. 

 The linings are not affected because of the short time 

 during which this slag is acting, and also because 

 of the comparatively low temperature. The charge 

 is then finally blown in the ordinary way, giving a 

 slag containing 14 to 20 per cent, of phosphoric 

 anhydride, 95 per cent, of which is in the soluble 

 condition. The addition of oxide distinctly improves 

 the yield, and the process is said to be working 

 thoroughly successfully. Week-end metal is cast into 

 pig beds and put on the market for foundry purposes, 

 which cannot be done with basic pig (b), as it is 

 only suitable for conversion into steel by the basic 

 process. A. McW. 



NOTES. 

 Prof. T. G. Bonney, F.R.S., will be the president of 

 the British Association at the meeting to be held nt 

 Sheffield next year. 



/We have to announce, with deep regret, that Dr. Arthur 

 Gamgee, F.R.S., emeritus professor of physiology, Uni- 

 versity of Manchester, and late FuUerian professor of 

 physiology in the Royal Institution, died in Paris on 

 Monday, March 29, at sixty-seven years of age. 



The Anthropological Society of Paris will celebrate the 

 jubilee of its foundation on July 7-9 next. The society 

 was founded in 1859 by Broca. 



The annual meeting of the German Hansen Society of 

 Applied Physical Chemistry is to be held at Aachen on 

 May 23-26, immediately before the International Congress 

 of Applied Chemistry in London. Among the subjects to 

 be discussed is the application of physical chemistry to 

 metallurgy. 



